A Phoenix man pleaded guilty on Friday to first-degree murder of his toddler nephew who died in 2012, according to court officials.

On July 11, Manuel Antonio Gonzalez, 26, changed his plea to guilty of first-degree murder of his 22-month-old nephew Xavier Martinez, according to a spokeswoman for Maricopa County Superior Court.

Gonzalez was arrested in late October 2012 on a series of allegations, including child abuse and first-degree murder, according to court documents.

On Oct. 19, 2012, Phoenix police responded to a drowning call near 71st Avenue and Durango Street, according to court documents. The toddler was found unresponsive and pronounced dead at Phoenix Children's Hospital a short time later.

Gonzalez was at his home on the 2000 block of South 71st Lane with his two children, ages 5 and 3, and Martinez, his wife's sister's son.

Martinez's mother, Maricela Becerra-Rodriguez, had left her son with Gonzalez for a short time while she went to the store with a neighbor, court records indicate. She returned home to police officers on the scene.

Police said Gonzalez initially told them that he left the three children in the home and went to the garage, where Martinez shortly followed, court documents show.

Gonzalez said he left Martinez unattended while he checked on a noise from inside the home and returned to a yell coming from the north side of the home.

Gonzalez said he found Martinez face down in a puddle of water, according to court records. He said Martinez was gasping for air and vomiting.

Court documents show Gonzalez told police he ran to a neighbor's home and called 911. Operators instructed him to began to performing CPR on the child before officials arrived, Gonzalez said.

Gonzalez was confronted with evidence that didn't match with his initial story and admitted to police that he lied, according to court records.

Gonzalez then told police he witnessed the toddler playing with the hose on the side of the house and that this was a normal occurrence. He said he took a drink from the hose and let Martinez do the same.

He then admitted to walking away from the child without turning off the hose and stated he felt the drowning "was his fault" because of this.

But police found evidence at the scene of a hose located on the south side of the home near an area with hard-packed dirt that wouldn't allow for a puddle to form, according to court documents.

Police also found a bloody towel and soiled children's clothing inside the home.

Fire officials on-scene felt the drowning call was suspicious and said the toddler's injuries did not match those of a drowning victim, according to reports from the time.

After further diagnosis, officials said the injuries did not match Gonzalez's story and that they were consistent with injuries of child abuse.

Gonzalez denied hitting the toddler and told police he didn't know how the towel and clothing ended up in the home.